• Question: If heat is just the proximity and interaction of particles, why can a lack of heat or too much heat be harmful to us?

    Asked by anon-177347 to Urslaan, Nicola, Helen, Becky, Andrew on 9 Jun 2018.
    • Photo: Urslaan Chohan

      Urslaan Chohan answered on 9 Jun 2018:

      Collisions between bodies is just two objects crashing together, but it can cause massive amounts of damage and carnage if two objects crash at high speeds! Similarly, heat is just a physical quantity, but too much of it can push particles out of place or stop systems from working. That’s what happens in us – too much heat causes our skin to burn and can damage internal organs. Eventually this can be fatal. Too little heat stops our chemical reactions from occurring in our bodies, which causes systems to shut down. Don’t forget, heat is an energy that drives chemical reactions too! Our brain also checks the temperature of our body (a part called the hypothalamus), which drives different bodily reactions to maintain body temperature (a process called homeostasis). When the temperature drops in the absence of heat, the body starts to shiver. Eventually we start to have delusions and confusion, and the organs eventually start to shut down. The blood vessels start to contract to lower heat loss. This is the body trying to maintain body heat. Likewise, when we’re too hot, the body sweats. When the body runs out of water, we start to become tired and eventually collapse, leading to death. So the right amount of heat is very important!

    • Photo: Andrew Singer

      Andrew Singer answered on 9 Jun 2018:

      In your question, you use the word ‘particles.’ I’ll use that word to mean molecules. Biology on earth has evolved to operate in a range of temperatures, from well below -40C to well above 50C. The perfect temperature for each organism will vary depending on where it normally lives. When an organism such as a bacteria experiences cold temperatures, the molecules around it are moving less than when it is hot. The fact that things move slower when its cold means that biology struggles when it’s cold unless it adapts its biology to life at cold temperatures–and that’s what they do! They make different molecules that are more ‘fluid’, allowing the biology of life to continue without freezing. The same happens at hot temperatures–life adapts. Life at hot temperatures starts using molecules that are less fluid (the opposite of when it was cold). The antifreeze in a car is a good example of how we have modified cars to work in very low and very hot temperatures. The antifreeze is made of chemicals that make it difficult to freeze the water the car uses when it’s cold and prevents the very same water from boiling when the car is hot. Biology has evolved its own antifreeze–these chemicals help to modify the chemistry of cells to still work in extreme conditions.

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